Sunscreens are substances or compositions applied to the skin to protect the skin from sunburn caused by the sun's ultraviolet rays. When uniformly applied to the body, sunscreens can be highly effective in protecting against sunburn. However, sunscreen failure can occur when areas of the body are missed because the sunscreen is hard to see or visualize after being applied or rubbed onto the skin. Children are at greater risk of sunburn than adults, since coverage on children's skin tends to be more incomplete, uneven or inconsistent.
U.S. Pat. No. 5,747,011 was issued to Ross et al. and assigned to Schering-Plough HealthCare Products, Inc. This patent is hereby incorporated herein by reference in its entirety. This patent discloses a colored, sunscreen emulsion which employs a water-soluble dye or a blend of water-soluble dyes. The color imparted by the dyes is said by this patent to substantially disappear when the sunscreen emulsion dries after it is spread on the skin and/or is rubbed out. The coloration in the sunscreen is said to enable the user to more effectively protect against sunburn by allowing more complete and uniform coverage of the sunscreen on the skin.
The sunscreen emulsion disclosed in the Ross et al. patent includes at least one water-soluble dye that imparts a color other than white to the sunscreen emulsion, such that when the sunscreen emulsion dries after it is spread on the skin and/or is rubbed out, the color is said to substantially disappear. Various water-soluble dyes are listed in the patent as useful. The Ross et al. patent specifically discloses that oil-soluble dyes tend to stain the skin (see col. 2, lines 39-42), and thus indicates that they should not be used in a colored sunscreen that is intended to at least substantially lose its color upon or shortly after application to the skin.